CL https://chromium-review.googlesource.com/c/chromium/src/+/977912 changes code that is macOS/iOS specific and thus cannot cause a failure on Windows (code is in file that only compiled on macOS/iOS or behind OS_MACOSX).

However, PushMessagingBrowserTest.LegacyUnsubscribeSuccess failed on win7_chromium_rel_ng, thus the test must be flaky.

https://ci.chromium.org/buildbot/tryserver.chromium.win/win7_chromium_rel_ng/148998